Characterization of promoter elements directing Mona/Gads molecular adapter expression in T and myelomonocytic cells: involvement of the AML‐1 transcription factor

Monocytic adaptor (Mona, also called Gads) is a molecular adaptor implicated in T cell activation and macrophage differentiation. The objective of this study was to identify elements regulating specific expression of Mona/Gads in human T cell and myelomonocytic cell lines. We first confirmed that the −2000 to +150 genomic region relative to the Mona gene transcription start site is sufficient to direct specific reporter gene expression in T cell lines, Jurkat, and MOLT‐4 and in the immature myeloid cell lines, KG1a and RC2A. Deletion analysis and electrophoresis mobility shift assay identified several cis regulatory elements: overlapping initiator sequences, one interferon response factor‐2 (IRF‐2)‐binding site at position −154, one GC box recognized by Sp1 and Sp3 at position −52, and two acute myeloid leukemia (AML)‐1 binding sites at positions −70 and −13. Site‐directed mutagenesis experiments indicated a key role of AML‐1 for driving Mona expression in T cells and myeloid cells, and involvement of Sp1/Sp3 and IRF‐2 transcription factors to modulate Mona expression in a cell‐specific manner.